Truth in Geology Series

The Truth About Varves

For years young
earth creationists have made a frontal assault upon a geologic feature known
as varves. In this article, I will explain what a varve is, what the
standard geologic thinking is concerning varves, and the young earth
arguments against varves. At the end of each claim, I will show the flaws
in the young earth arguments against varves. In the end, you will see that
the claims fall far short of disproving the standard geologic thinking about
varves.

What are Varves? The Standard
Geologic Explanation

Horizontal
bedding structures exist in many types of depositional environments, such as
lake bottoms, gently sloping beaches, or in a deep marine environment.
One of the main categories of horizontal bedding is known as "rhythmites."

A rhythmite is
bedding that is in a repetitious sequence, generally thin, and contains
alternating types of sediment particles. The varve is a type of
rhythmite. In a varve, there are alternating layers, with a thicker,
coarser layer, followed by a thinner, fine-grained layer.

The standard
explanation for the alternating layers states that the summer months
represent the thicker, coarser layer. This is due to the increased
precipitation during summer, thus you have more water entering the lake.
The increased water flow has the capability to carry larger sediment
particles, hence the thicker summer layer has larger grain sizes than the
winter layer. During winter, when the water is not entering the lake,
the still waters allow the deposition of fine-grained sediment.

This
model provides an excellent fit for the cyclic pattern of our four weather
seasons during the year. Thus, each varve couplet is considered to
represent an annual layer of sediment accumulation.

The most
well-known of the varve formations in the world is the Green River Formation
of the western United States. For the remainder of this article this
formation will be referred to as the GRF. The GRF contains up to six
million layers. Using the standard varve explanation above, that would
mean this formation represents over three million years of sedimentation.
Because of this, young earth creationists have always sought to tear down
the arguments about varves, seeking to undermine the three million years
that they represent. Let's look at their claims.

Young Earth Arguments Against Varves

Young earth arguments against varves
appear in many locations. To simplify matters, here I will consider their
arguments from websites, which are easily accessible to you as you read this
article.2,3,4,5 Basically, most of the arguments against
varves amount to a discussion of the length of time it takes to deposit a
varve. To dispute the bi-annual cycle of standard geology, they point to
several instances of finely laminated sediment which are not bi-annual.
These are discussed separately.

CLAIM: Young earth authors mention the
claim of the modern lake that has been observed to create more than two
annual layers. This would give support to the fact that varve layers could
be from individual storm events, thus if you had an area that had 40 storms
in a year, you could have 40 layers. In the example they use, there are
300 to 360 layers which had formed over a 160 year period. In
another article, they mention a Swiss lake where five pairs of varves built
up in a single year. (I don't know if this is the same lake in each case.)

REBUTTAL: First, the 300-360 layers
in 160 year period. Since varves are couplets, or two layers annually,
twice 160 gives you 320, so this example fits the standard geologic
explanation for varves. I'm not sure what they hoped to gain with this
argument, since it clearly presents no argument for varves forming at more
than the two per year rate.

For the Swiss
lake example, let’s assume that they are
correct, and varve couplets contain layers from individual storm events. In the
example of the Swiss lake, there were five pairs of varves annually. For
the sake of fair play, lets say that a pair represents a storm, thus
there are 5 storms per year represented. In the GRF, there are over 6
million varves. Dividing this by 5, it would take 1,200,000 years to deposit
all the layers of the GRF.

Now, let’s assume there was more rain at the GRF
location. Let's assume it rains 40 times a year at the GRF location. This would give you forty
couplet layers. There are 6 million varves in the GRF. At an accumulation rate of
40 couplets per year, it would take 75,000 years to deposit all the varves.
This is much longer than the 6,000 to 10,000 years that young earth
creationists claim as the age of the earth. In order to get down to
the 10,000 year range, you would need 300 storm events per year for the last
10,000 years. At this rate, the storms would be so constant that you
would not get the finely layered couplets that we see in the rocks, nor is
it realistic to say that it rained that much in that location over the last
10,000 years. (Lower it to 6,000 years, which most young earth
creationists claim as the age of the earth, and you have 500 storms per
year!)

Although the
five couplets of the Swiss lake is something to consider, it does not
provide a good rebuttal to the standard geologic model for varves.

CLAIM: Young earth creationists use the
argument of the two volcanic layers. There are two volcanic ash layers in
the GRF. Volcanic ash layers are special because the volcanic ash is viewed
as a single event, and wherever it appears in the formation, it can be
assumed that it is the same age. This is important because it can date the
ages of the layers relative to each other. As the young earth argument
points out, between these two ash layers, the number of varves varies. They
state, “The number of shale layers between the ash beds varied from 1160 to
1568, with the number of layers increasing by up to 35% from the basin
centre to the basin margin! The investigators concluded that this was
inconsistent with the idea of seasonal ‘varve’ deposition in a stagnant
lake.

REBUTTAL: Actually, this supports the
old earth model. Please note that the number of varves increased as
you went from the center of the basin to the outside edges. To fully
understand this, consider this simplified diagram of a closed lake system.

With the GRF, we have a closed
basin, i.e. the water is not draining out anywhere. The four black lines
are rivers bringing in fresh water. The sources of the sediments forming
the varves are brought into the lake by the rivers. Once the waters enter
the lake, they immediately slow down, and the sediment that they carry falls
out of suspension to the lake floor. We would expect to see the most layers
closer to the basin edges, where the water velocity drops, as evidenced by
the darker blue area. The closer we get to the center, we would expect to
see less sediment from the rivers, hence, less varves. Therefore, the
layers between the volcanic ash would reflect this pattern of less layers in
the middle.

This young-earth argument has no merit. Why then did the
scientists they mention not see this? We don’t know. Either they
overlooked this simple observation, or they saw only what they wanted to see
(i.e. they were young-earthers).

CLAIM: Third, they discuss the formation
of many layers quickly at Mount Saint Helens. They use this as evidence
that it doesn’t take long periods of time to deposit thin layers of
sediment.

REBUTTAL: I agree, you can deposit
volcanic ash in fine layers very quickly. Unfortunately, the GRF is not
made up of volcanic ash layers. Of the six million varves, only two
volcanic events appear. If the GRF were totally volcanic, then the young
earth creationists would have a point. As it is they are comparing apples
and oranges. There is no relation between Mt Saint Helens and the GRF,
since they are two completely different geologic sedimentation systems.

CLAIM: Fourth, they use the argument
from a hurricane. Hurricane Donna in 1960 left a six inch thick layer of
thinly laminated mud-lime.

REBUTTAL: Again, I agree that a
hurricane can lay down thinly laminated sediment quickly. However, the GRF
is a lacustrine environment, not a marine environment. None of the layers
of the GRF can be attributed to a hurricane. Again, the young earth
creationists are comparing apples and oranges.

CLAIM: One of the most popular
arguments young earth creationists use is fossils. They claim that GRF fossils
must have been buried rapidly because the fossils that are recovered are in
excellent shape. Also the individual fossils are contained in multiple
layers of varves. For example, if a fossil fish is
contained in 10 varve layers, then that would represent five years of
deposition by the standard geologic model. The claim is that the fish would
have decayed long before the five years were expired, thus the burial of the
fish must have happened rapidly. They claim that “a fish carcass, even if
it did get to the bottom of a lake would not remain undecayed and
unscavenged for several years, slowly being covered by seasonal
deposits.” To this, they add mention of the study where fish decayed in
a week’s time when lowered into a marsh environment.

REBUTTAL: There are many factors that go
into fossil preservation. Time is not the only consideration. However,
time is the only variable that the young earth creationists allude to. The
condition of the water in the lake is extremely important. Consider the
bog people of Europe. These bodies are very well preserved after many
years, in some instances in excess of 2,000 years. In terms of the GRF,
that would be 4,000 varve layers. How could this happen?

Decay is slowed
dramatically in conditions of anoxic water. In other words, there is virtually no oxygen at the bottom of the lake, and
thus other living organisms could not reach the bottom of the lake to scavenge the
carcasses. This is what we see with the bog people. When you
throw in the two additional variables of oxygen level and scavenger
population, the young earth theory clearly does not pose a threat to the
standard geologic explanations.

CLAIM: Young earth creationist Walt
Brown’s so-called theory of liquefaction seeks to explain the varves away
also5. A good rebuttal to this claim can be
found here.
Some important points to consider...if all fossils were the result of the
flood, then one would expect all fossils so show evidence of rapid burial,
but in fact, only a small minority fit the rapid burial model. Second,
if liquefaction sorted the layers of sediment quickly, it would also sort
the fossils together, however, fossils occur all throughout the GRF.

Conclusion

Although the
young earth arguments provide food for thought with varve geology, they do
not come close to tearing down the standard geologic thinking about varves.
They amount to empty arguments without scientific merit.

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